Shattered Blanks

[Sappheiros]

It's been a while since I've logged on. Things have been pretty busy and crazy, and I promise I'll post some new pens soon, but I've been having a big problem lately... It feels like every other pen blank I turn shatters either on the end or almost right down the middle. I know rushing can be an issue, but I try and take my time as best I can.

Factors:
- The garage is very cold, but I do have a heater going.
- When gluing the blank to the tubing, should the glue leave no gaps between the tubing and blank? I used to do one line of glue down the tube but lately I've been doing two.
- I use the Easy Wood Tools Easy Pen Turner and the Easy Wood Tools Full-Size Easy Finisher. They should't be dull since I haven't used them much.

It's all really disheartening. Do I turn in the towel for the winter? What do you all do? What should I do?

 

[maxwell_smart007]

My shop is cold too - I can't seem to get it above 10 or 12c...

What thickness of CA do you use? I use medium for gluing in tubes - twist when you put it in, so that it evenly coats the whole tube. I roughly squiggle it on the whole blank, adn then twist when I insert it.

 

[Lucky2]

Avi, just how cold is your shop? You do realize that your glue won't work properly, unless it's at a certain temperature right? I doubt that this is the issue, but, it could be a contributing factor.
Len

 

[1080Wayne]

I assume these are plastic blanks of one kind or another . If the blank is very brittle . it is possible to initiate small fractures while drilling by using a dull drill and/or pushing the drill through too fast . You may hear a cracking sound while drilling , but the blank may hold together and wait until the next operation to complain further . That would be when you attack it with a less than sharp carbide tool . It is also possible to crack a perfectly sound brittle blank just by using a dull tool .

My guess would be that your tools are not as sharp as you think . 100% filling of the gap between blank and tube is also important , as mentioned above . Some of us use Gorilla glue or equivalent polyurethane glue rather than CA , because it expands to fill the gaps .

 

[randyrls]

Avi; Several possibilities; Some have been mentioned by others. The cold causes acrylics to become more brittle.

Drilling: Do you drill thru the end of the blank? The drill bit breaking thru can cause cracks in the blank that are not obvious until turned down. Solution; cut long, drill short and cut off the excess.

Glue: Use medium or thick CA. Block the inserted end of the brass tube. Put a dollop of glue inside the drilled hole. Insert tube with a twisting motion. The glue should come out all around the other end of the brass tube. Solution; Use more glue than you think is needed.

Pen Mill: The pen mill can cause cracks in the end of the blank. Solution; Use a sanding jig to mill the ends of the blank.

Blank corners: The impact forces on a corner of the blank can cause it to stress fracture. Solution; Knock the corners off the blanks with a sanding disk.

Dull tools: Get a credit card sized diamond hone, remove the carbide bit, and give it a touch up. Lay bit face down on hone. Do a figure 8 pattern, turn 90 degrees and repeat three more times. water lube. I do this every other pen.

 

[robutacion]

It's been a while since I've logged on. Things have been pretty busy and crazy, and I promise I'll post some new pens soon, but I've been having a big problem lately... It feels like every other pen blank I turn shatters either on the end or almost right down the middle. I know rushing can be an issue, but I try and take my time as best I can.

Factors:
- The garage is very cold, but I do have a heater going.
- When gluing the blank to the tubing, should the glue leave no gaps between the tubing and blank? I used to do one line of glue down the tube but lately I've been doing two.
- I use the Easy Wood Tools Easy Pen Turner and the Easy Wood Tools Full-Size Easy Finisher. They should't be dull since I haven't used them much.

It's all really disheartening. Do I turn in the towel for the winter? What do you all do? What should I do?

G'day Avi,

Sorry to hear about your troubles but, knowing that you got some blanks from be and some were Banksia's, I wonder if you having troubles with my blanks...??

Please let me know...!

Cheers
George

 

[mike4066]

It's been a while since I've logged on. Things have been pretty busy and crazy, and I promise I'll post some new pens soon, but I've been having a big problem lately... It feels like every other pen blank I turn shatters either on the end or almost right down the middle. I know rushing can be an issue, but I try and take my time as best I can.

Factors:
- The garage is very cold, but I do have a heater going.
- When gluing the blank to the tubing, should the glue leave no gaps between the tubing and blank? I used to do one line of glue down the tube but lately I've been doing two.
- I use the Easy Wood Tools Easy Pen Turner and the Easy Wood Tools Full-Size Easy Finisher. They should't be dull since I haven't used them much.

It's all really disheartening. Do I turn in the towel for the winter? What do you all do? What should I do?

Here's a few things I do when its cold, but I'll be the first to admit I'm a fair weather turner until I get the heat/insulation finished in the garage.

I've had tube separate/break due to CA glue failure and switched to Loctite 5 minute epoxy and haven't had any fail since. Bonus i haven't glued myself to a blank in months.

This is probably stuff you are already doing, but here's my routine.. rough sand paper on the tube, reverse paint the blank and give it time to cure (not just dry there is a difference), dental wax in one end of the end of the tube to keep the epoxy out, mix the epoxy and insert the tube with a twisting motion puling it in/out to make sure I get full coverage.

As for the ends chipping:

Once its rounded try working the edges from the outside in, you'll be supporting the cut instead of pushing out towards the edge.

Also get everything up to a reasonable temp, 30-40 is pretty cold for CA/Epoxy/Paint and they won't cure nearly as fast. When its this cold I do my glue-ups /painting in the house instead of the garage. This also gives the blank a chance to warm up.

You can always rotate the carbide bits as well if you think they may not be sharp.

Hope this gives you some ideas.

 

[Dalecamino]

Are you keeping your tool at center or just above? If you get below the center line of the blank it could be your problem.

 

[thewishman]

Glue should be applied so that all of the tube is glued to all of the blank.

Shattering - bring the blanks and drill bits into the house to warm up, after drilling, bring the blanks and glue in to warm up. After the glue has cured, keep the blanks inside until you're ready to turn them. I keep the next blank I will use in my pocket, to keep it warm.

 

[WriteON]

I know rushing can be an issue, but I try and take my time as best I can.

There is no substitute for taking your time. And rush jobs take longer as we do them over. Start out with sharp tools and take your time. Slow down...bet nothing shatters or chips. It's not the gluing or temperature that causing the issues.

 

[mredburn]

How cold are your blanks when you start to drill them? You can heat the shop but if the blanks are still cold internally, Thermal Expansion will cause them to fail. A cold blank that heats up suddenly from drilling will crack and fail. I suggest you keep the blanks in a warm environment and take them out to the shop when your ready to work them.
You may want to go to a 5min epoxy and cover the entire tube with glue. I will spread glue around the tube and inside the blank with a toothpick or Q-tip to make sure I have complete coverage. Twist as I insert the tube out past the end of the blank and then back in. If I use Ca I Use a medium or thick version but prefer to use epoxy.

 

[BigNick73]

- When gluing the blank to the tubing, should the glue leave no gaps between the tubing and blank? I used to do one line of glue down the tube but lately I've been doing two.

No gaps. I like to use 5 minute epoxy over CA for this reason. It's thicker and I have more time to work with it so I can be sure the tube is well coated. After I square then ends I usually end up cleaning glue out of the inside of the tube as well, so use lots. I had a few blowouts with my early pens because the blanks wouldn't be glued to the tube in places and those parts would break loose after being turned thin.

 

[mecompco]

Great advice above. I agree--switch to epoxy (I put on the nitrile gloves and smear it all over the well-scuffed tubes). Let 5 min epoxy set for 24 hours.

Drill slowly and keep the bit cool. Don't drill through the blank--drill it, then cut it off to length.

Don't use a pen mill--a disc sander on the lathe is the answer.

Use sharp tools and don't get too aggressive, especially while the blank is still squareish.

Since I learned these lessons (the hard way), I've not had a problem.

Regards,
Michael

 

[Sappheiros]

Thanks for all of the advice! I need to consider it all and reassess my situation. I'm flying out to Cali for a bit under a week, so I'll be back with energy!

George, I was just using a couple acrylic blanks I had before. I wanted to get to the bottom of that before trying out the exotics! I know they'll turn real beauties!

 

[farmer]

machining

Thanks for all of the advice! I need to consider it all and reassess my situation. I'm flying out to Cali for a bit under a week, so I'll be back with energy!

George, I was just using a couple acrylic blanks I had before. I wanted to get to the bottom of that before trying out the exotics! I know they'll turn real beauties!

Depending on what style of lathe you have.

 

[TDicaprio]

Randy-
Agree with all of your points/advice. I do the same and have very few issues with acrylic blanks...unless they are poor quality and/or riddled with voids.

 

[dachshund1]

It's been a while since I've logged on. Things have been pretty busy and crazy, and I promise I'll post some new pens soon, but I've been having a big problem lately... It feels like every other pen blank I turn shatters either on the end or almost right down the middle. I know rushing can be an issue, but I try and take my time as best I can.

Factors:
- The garage is very cold, but I do have a heater going.
- When gluing the blank to the tubing, should the glue leave no gaps between the tubing and blank? I used to do one line of glue down the tube but lately I've been doing two.
- I use the Easy Wood Tools Easy Pen Turner and the Easy Wood Tools Full-Size Easy Finisher. They should't be dull since I haven't used them much.

It's all really disheartening. Do I turn in the towel for the winter? What do you all do? What should I do?

I'm also new to the hobby, so take this for whatever it's worth. For acrylics, I find the Easy Woods finishing tool to be MUCH easier to use than the pen turner - and I only resort to the latter to even out the final shape and hone down the diameter. Also, being enamored with the idea of having chisels that "don't need sharpening," I caught myself using these tools beyond the point they were capable of delivering their best cutting edge. I suspect this (and a lack of experience), more than anything, contributed to my own destruction of several acrylic blanks on the lathe. Of course, YMMV - my shop is also reasonably warm, I glue my tubes with epoxy etc.